The book contains 200 excellent puzzles 7x7 at the level of Hard to Very Hard. Hard puzzles 100, Very Hard puzzles 100. -All riddles have only 1 solution. -2 puzzles per page. -The font size is correct you will not have to strain your eyes when solving puzzles. -High quality paper and print (all puzzles read well, easy to write with pen and pencil without worry of bleed-through). Numbricks is a type of logic puzzle. It is played on a rectangular grid of squares. Some of the cells have numbers in them. The object is to fill in the missing numbers, in sequential order, going horizontally and vertically only. Diagonal paths are not allowed.